Calcium Side Effects, Interactions and Warnings

High intake of dietary calcium appears to decrease risk for symptomatic kidney stones, whereas intake of supplemental calcium may increase risk. Because dietary calcium reduces the absorption of oxalate, the apparently different effects caused by the type of calcium may be associated with the timing of calcium ingestion relative to the amount of oxalate consumed. However, other factors present in dairy products (the major source of dietary calcium) could be responsible for the decreased risk seen with dietary calcium.- Ann Intern Med 1997 Apr 1;126(7):497-504 -- Comparison of dietary calcium with supplemental calcium and other nutrients as factors affecting the risk for kidney stones in women. -- Curhan GC, Willett WC, Speizer FE, Spiegelman D, Stampfer MJ.

The mechanisms causing drug-fortified food interactions are the some well-known mechanisms that cause other drug-mineral interactions. Certain drugs may exhibit decreased absorption due to chelation and adsorption. Other drugs may have decreased absorption or increased excretion due to changes in gastric and/or urinary pH. The results of such interactions may be clinically insignificant or severe, including treatment failure, frequent dose changes, antibiotic resistance, and increased morbidity and mortality.- J Clin Pharmacol 2002 Apr;42(4):437-43 --
Is it really OK to take this with food? Old interactions with a new twist. -- Wallace AW, Amsden GW.

Use caution when combining calcium with prescription medications. Adverse interactions may occur.